linux-kernel - Re: [PATCH] Documentation: dmaengine: Add a documentation for the dma controller API

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Message-ID: <20140802190615.GO3952@lukather>
Date:	Sat, 2 Aug 2014 21:06:15 +0200
From:	Maxime Ripard <maxime.ripard@...e-electrons.com>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	Vinod Koul <vinod.koul@...el.com>,
	Dan Williams <dan.j.williams@...el.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	dmaengine@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
	Antoine Ténart <antoine@...e-electrons.com>,
	Thomas Petazzoni <thomas@...e-electrons.com>,
	Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
	Boris Brezillon <boris@...e-electrons.com>,
	Matt Porter <matt.porter@...aro.org>,
	laurent.pinchart@...asonboard.com, ludovic.desroches@...el.com,
	Gregory Clement <gregory.clement@...e-electrons.com>,
	Nicolas Ferre <nicolas.ferre@...el.com>
Subject: Re: [PATCH] Documentation: dmaengine: Add a documentation for the
 dma controller API

On Sat, Aug 02, 2014 at 04:17:14PM +0100, Russell King - ARM Linux wrote:
> On Sat, Aug 02, 2014 at 04:49:25PM +0200, Maxime Ripard wrote:
> > In the case of the call to device_control, especially in the
> > DMA_SLAVE_CONFIG case, but that also applies to pause/resume, are the
> > changes supposed to be immediates or can they happen later?
> 
> pause/resume are expected to operate synchronously on the channel.
> When asking for the channel to pause, the channel must be stopped
> before the call returns.
> 
> In the case of channel configuration, that should have no effect on
> any previously queued transfer - in other words, changing the channel
> configuration only has an effect when subsequent transactions are
> prepared.

Ok, thanks!

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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